Our current setup has PHP scripts being served by Apache using mod_php. We have just developed a new script that needs to be run through CGI (it's using pcntl to fork off some processes) instead of mod_php. Can someone give me an example configuration for this? Ideally we'd be able to have all the scripts run through mod_php except this one, but if we have to run them all through, then I can live with that.

CGI is a COMMON GATEWAY INTERFACE ... i.e. you don't need to set it up for particular languages. However, Apache normally determines what to do with a file based on the filename extension (e.g. file.cgi versus file.php)

Your Apache configuratin is most likely already setup to handle CGI programs, you probably only need to do two things